This project proposes to continue an investigation of stereospecificity in biological reactions, particularly the ability of enzymes to discriminate between like groups attached to a prochiral center. Five specific goals are outlined for the renewal period: 1. To examine the streospecificity in three separate biosynthetic pathways to beta-alanine: a) Metabolism of uracil; b) Decarboxylation of aspartic acid; c) Amination of acrylyl coenzyme A. 2. To investigate the stereochemistry of carbon-nitrogen bond cleavage in the proline reductase reaction. 3. To determine the absolute specificity of the hydroxymethyltransferase reaction in hydroxymethylserine. 4. To investigate the stereospecificity of hydroxylation during enzymatic conversion of phenylalanine to mandelonitrile in the millipede. 5. To determine the absolute configuration of the monoterpene alcohol artemesia alcohol.